•Temperature monitoring was carried out in a TRIGA® reactor in the fuel, core, and pool.•The experimental results were compared with the theorical results.•The tests provided an understanding of the thermo-fluid dynamics of the TRIGA® reactor.•The experiments confirm the efficiency of natural circulation in removing heat.•A power measurement channel based on fuel temperature was developed. The natural convection and forced cooling experiments were conducted to confirm the cooling capability in the IPR-R1 TRIGA® nuclear research reactor. Temperature measurements were carried out in several locations such as: at the coolant inlet and outlet in the core channels, at various pool heights, and at the centre of an instrumented fuel element. The temperature monitored by the instrumented fuel element was performed with it positioned in all the core rings and at different operating powers. A new way of measuring the power released by nuclear fissions in the core using thermal processes has been developed. To monitor temperatures and power, a Data Acquisition System (DAS) was used. The information acquired during the experiments provides an exceptional representation of the IPR-R1 TRIGA® reactor’s thermal performance. The experiments confirm the efficiency of natural circulation in removing the heat produced in the reactor core by the nuclear fission.